Process of making molybdenum steel



Patented" 4, 1927.

UNITED STATESV'VPATENT oFFlcE.

UREDEBIJK' BECKET, OF NEW YORK, N.-Y., AS SIGNOI B T ELEGTROMETALLURGICAL COMPANY, A CORPORATION OF WEST VIRGINIA.

PROCESS OF MAKING- MOI LYBDENUM STEEL.

No Drawing.

direct processes, i. e. by processes which do not involve thepreparation of metallic molybdenum or of a molybdenum alloy. In thepractice fof these direct processes it has hitherto been customary tointroduce molyb- 80 denum into the steel furnace or crucible as an oxideof moiybdenum or as a molybdate. When derived from molybdenite ore orconcentrate, preparation of the oxide or of the molybdate -has hithertoinvolved a roasting 2 operation whereby the molybdenum contentof the-orewas converted into molybdenum oxide or,- under certain conditions whenthe roasting charge contained lime or iron oxide, into ca cium molybdateand iron molybdate, respectively. Even when any of the aforesaidchemical compounds of molybdenum have been prepared fr'om the ore in thewet way by leaching and precipitation methods, oxidation or preliminaryroasting of the molybdenite or a charge mixture containing ithas beencharacteristic of the process-as a whole.

According to the present invention molybdenum sulfid is brought as suchinto reactive 4o relation to the steel bath. My investigations haveshown that under suitable conditions of practice the molybdenum contentof the. sulfid is recovered completely or in amount sufliciently high torepresent an entirely practicable recovery ratio; and what is of vitalimportance from the commercial aspect, this recovery is effected withlittle or no attendant increase in the sulphur content of the finishedmetal. In other words, in the practice of the.present invention the unitcost of the molybdenum contained in the Application filed November 19,1925. Serial No. 70,188.

finished steel may in good practice be made to approach very closely,and practically to equal, that of the molybdenum content of the originalore or concentrate.

I The following specific examples illustrate preferred procedures, ascarried out in the basic electric furnace:

I. Molybdenite concentrate analyzing 54.15% molybdenum and correspondingapproximately to 90% MOS was added to a heat of steel in a basic-linedelectric furnace in such amount that them'olybdenum in the concentrateadded was 0.43% of the weight of the .steel in thefurnace. The additionwas made in this case after the first or oxidizing slag had been removedbut prior to the attainment of those strongly reducing conditions whichare characterized by a slag of the,carbide type. This was followed byfurnace additions of washed metal, highcarbon ferromanganese andlow-carbon ferrochrome, in the order stated. Three hours after theaddition of molybdenite concen trate to the bath, and thirty minutesafter the addition oflow-carbon ferrochrome, the heat was poured andtreated in the ladle with ferrosilicon. The finished steel had thefollowingcomposition:

Percent.

C 0.37 Si 0.35 Mn 0.81 P 0.011 S 0.012 Cr 1.12 Mo 0.44

addition of high-carbon ferro-manganese. ,The amount of molybdenum thusadded as molybdenite was equivalent to 0.40% of the metal charge. Thesteel, which was treated in the ladle with ferrosilicon, had thefollowing compos1tion:

Percent. G 0.40 Si 0.27 Mn 0.68 P 0.012 S 0.017 Cr 1.12 Mo 0.35

erating agents may be added, such as bori c oxid, glass, fiuorspar,silica and basiccompounds, including compounds of the alkali metals,without departure from the present invention, provided that the processof incorporating said fluxes and agglomerants preserves the chemicalidentity of the molybdenum sulfid, or provided that said process bringsabout only in part the chemicalconversion of the sulfid into otherproduct or products. 7 It'will be understood by those skilledfiii theart that the temperature and composition of the steel and of the slag,as well as the time allowed for their reaction with molybdenum sulfid,may exert a marked effect .uponthe percentagerecovery of molybdenum inthe finished steel, and also upon. the sulphur content of the latter.More especially in the caseof open-hearth practice it is preferableunder certain conditions to add the molybdenite in successive batchesrather early inthe progress of'the heat, and to distribute it over thesurface of the bath, rather than to make the entire addition at one timeand at one location within the furnace.

I claim:

1. Process of making molybdenum steel, comprising bringing molybdenumsulfid into reactive relation with a steel bath in the absence ofabnormal reducing conditions.

2. Process of making molybdenum steel, comprising bringing molybdeniteinto reactive relation with a steel bath inthe absence of abnormalreducing conditions.

3. Process of making molybdenum steel, comprising bringing a molybdeniteconcentrate into reactive relation with a steel bath in the absence ofabnormal reducing condit'ions.

4. Process of making molybdenum steel, comprising agglomeratingmolybdenum sul fid and bringing the 'agglomerate into reactive relationWith a steel bath in the absence of abnormal reducing conditions.

, In testimony whereof, I affix my signature, FREDERICK M. BECKET.

